TR4/4A My new 1967 TR4A IRS

[gubba]

Hi gang I just bought a TR4a IRS and It has the overdrive tranny...Now the age old question...What is the prefered weight oil recomendation for the overdrive tranny? 90 weight hypod or 30 wieght none detergent motor oil? I await your numerious replies.

 

[elrey]

Congrats! You are always safe with Castrol 20/50. There are a host of other brands and weights you may use. No doubt others will add in with their favorites. Plenty of folks use the same oil in the transmission/overdrive unit that they use in their engines, it simplifies things. Enjoy your new ride. What a fine model you have lucked into! :thumbsup:

 

[Mickey Richaud]

And PICTURES, please!

Mickey

 

[Geo Hahn]

I had used Valvoline 30W non-detergent for years and all was well.

Last change I switched to Redline MT90 based on a forum recommendation that suggested it might be as good or better. As I had used a Redline oil in my non-OD box for more than a decade I thought I'd give the MT90 a go. It too seems just fine.

I have never used a modern (detergent, etc) engine oil in either of my gearboxes so can't comment from experience on that.

 

[hondo402000]

I was told to use the same oil from GM that goes into corvettes, only 22.00 a quart. you dont want to use to slippery an oil or the cone clutch in the OD will slip. but my understanding is 90 weight gear oil and SAE 30 motor oils are the same as far as viscosity goes, they just have different specs

Hondo

 

[gubba]

Could someone refresh me on how to post an image.Regards

 

[tdskip]

30W non-detergent is a safe bet.

Now where are the pictures? :laugh:

 

[gubba]

I hope this worked.

 

[TR3driver]

Could someone refresh me on how to post an image.Regards

Easiest method, IMO, is to create an account on one of the various photo-sharing sites. I use PhotoBucket. With PB, you just let your mouse hover over the thumbnail of the photo you want to post on BCF, then click in the popup box where it says IMG code. Then go back to the window where you are composing your BCF post and hit Ctl-V. What you will see will look something like <div class="ubbcode-block"><div class="ubbcode-header">Code:</div><div class="ubbcode-body ubbcode-pre" ><pre>

</pre>[/QUOTE] but when others view your post, they will see your photo:

On the gearbox oil wars; the story I heard (supposedly originally from an ex-factory engineer) is that they were seeing too many warranty failures of the gearbox thrust washers when using non-detergent motor oil in the gearbox. So around 1960, they switched to officially recommending 90 weight GL4 gear oil. The "extreme pressure" additives were thought to provide better protection for the countershaft thrust washers in the gearbox.

I ran 20W50 Valvoline Racing (motor) oil for many years, based on recommendations from Ken Gillanders (British Frame and Engine) and Herman van den Akker (HVDA). The high levels of ZDDP (generally not found in non-detergent oils) should also help protect the washers, and indeed I had no problems that I attributed to the oil.

But I relatively recently switched to the Redline MT-90, and I love it! It really makes the main gearbox shift nice. Overdrive operation seems better too, but it's kind of hard to compare because I also adjusted the OD pressure at the same time.

 

[gubba]

Which one do you want? and like I thought three will be many answers about the oil.

 

[RJS]

Nice car (although I may be biased). When my OD tranny was rebuilt I am quite certain they used 80W/90 GL4 gear oil. At least it sure smelled like gear oil when I changed it. All worked very well.

When doing a routine fluid change I went with SAE30 non detergent motor oil based on recommendations. Everything worked but noticed I was getting notchy shifting going into 3rd gear, especially when fully warm.

So, after a year I then moved to Redline MT90 and back to normal. Very satisfied. Had I not gone the synthetic route I would have used Valvoline 20W-50 racing (non detergent) motor oil. SAE30 is thinner and 20W-50 motor oil is closest in weight to the 80W90 gear oil (not a 100% perfect match due to viscosity ranges depending on temp). But, it is a very close match. I did not consider 80W90 gear oil again b/c the whole topic of sulphur in gear oil harming brass synchros. I am not convinced this is a problem but decided to be safe with synthetic gear oil.

Bob

 

[Nigel_TVR]

I have always used 30 weight non-detergent. The following article is from Quantumechanics:


We ran an experiment on overdrive oil. We rebuilt an A type overdrive unit and initially ran it with 30 weight non detergent motor oil. When spun up on our test bench at 1,000 RPM, it reached a normal pressure of 400 PPSI. When shifting the pressure dropped to 300 PPSI and quickly recovered to 400 PPSI. All was right in the world of overdrives.

We then drained the oil and replaced it with 10W30 multi grade oil. When spun on the test bench, initially it tested fine. However, after a few minutes of running, the oil pressure dropped to 300 and when shifting, to 200. Upon observation of the internals of the operating overdrive we found bubbles developing in the oil pump body and oil pump output passage. We surmised that the detergents in the oil were causing the oil pump to cavitate, and develop air bubbles as it pumped.

We then drained the oil again and replaced it with 90 weight hypoid oil. This time the oil pressure jumped to 600 PPSI! When shifted, the pressure dropped to 450 PPSI, which made the shift immediate and harsh. After a few minutes of running the oil pressure actually began to climb even higher. (Which made no sense since we thought the oil would thin out and the pressure would drop). We finally shut it off at 750 PPSI as we did not want to damage the unit. Even though the overdrive unit was now in the non overdrive position (solenoid disengaged), the overdrive was now stuck in overdrive and would not come out. The higher pressure had driven the sliding clutch member so hard into the brake ring that the clutch return springs could not return it to the non overdrive position. A tap on the brake ring with a hammer (the universal overdrive release tool), shifted it back into the direct drive position. After running a number of these test with the same result we found what was happening. The oil holes in the accumulator sleeve are very small. The 90 weight oil was so heavy it could not escape from the accumulator chamber as fast as the oil pump could pump new oil into it. So even though the accumulator piston had passed the oil hole relief position, the pressure continued to build up because the oil could not leave the system as fast as it was being pumped in. The accumulator piston actually bottomed out in the sleeve (similar to coil bind on valve springs). When removed we found the accumulator spring had been compressed and was no longer useable.

After replacing the spring, we then tried automatic transmission fluid. We saw the same results as we did when we used the 30 weight non detergent oil.

We then tried synthetic oil and the unit also worked OK although it began to leak from all sorts of places it had not leaked from before.

Based on these tests we have since and continue to recommend the 30 weight non detergent motor oil as the best oil to use in the overdrives.

Some other experiences with customer overdrives over the years have reinforced this choice. For example, we found a Jaguar compact overdrive with a broken accumulator piston and bent spring when it had been used with 90 weight oil by the owner. When the piston and spring were replaced and the unit filled with 30 weight non detergent oil, it functioned normally. A customer LH overdrive unit that was filled with 90 weight oil "pulsed" between direct drive and overdrive without even being switched on electrically. When the oil was flushed and replaced with 30 weight non detergent oil the unit worked normally.

Other noted problems with overdrives filled with 90 weight are excessive wear on the oil pump plunger wheel and the eccentric cam, probably due to the higher pressures developed. Also the clutch lining seems to be more deteriorated in units with 90 weight oil than those with 30 weight oil.

The use of non detergent 30 weight oil does not seem to affect the transmission parts or function. Bearings, synchros, gears and hubs do not seem to function any less effectively with the non detergent 30 weight oil as with 90 weight gear oil.

So there it is gang, our scientifically based rationale for using and recommending 30 weight non detergent oil in Laycock overdrives. I welcome further discussion and feedback on this topic by anyone interested. As always, thanks for reading this article!

 

[TR3driver]

And does anyone really believe that Triumph delivered over 100,000 cars that suffered the ailments described above?

Elsewhere on the same site, you can read how the gearbox thrust washers are "too weak" and should be upgraded with expensive Torrington roller bearings. There seems to be a relationship there ...

 

[Geo Hahn]

...What is the prefered weight oil recomendation for the overdrive tranny?...

Aren't you glad you asked? Keep us in mind when you need to decide on brake fluid, tires & damper oil.

At least we can all agree that Triumphs are great cars!

 

[LBCs_since_1988]

I had the same experience as Bob on my '66 '4A with overdrive. I'd get a notchy if not crunchy shift into third when warm with 30W ND. Switch to Redline (MTL I believe) and it's much smoother. I was surprised as I thought my gearbox was ready for a rebuild.

 

[gubba]

The info on this forum is outstanding as always..and I thank all of you for your opinions. The reason I ask the question is that the car is running 30w nd and I to have this notchy shift to 3rd gear up and down. Strange as the tranny was completley rebuit by Quantumechanics a few years ago. My first thought is to change oil to Redline MT90 to see if the noise goes away. If not maybe I will just go HVDA on the bad boy and call it a day.

 

[RJS]

Glad to help. Would appreciate hearing back on this post if/when you change to MT90 and if it makes a difference on 3rd gear. Mine never grinded but, it took a few seconds delay for the engine speed to match before I could slide it into 3rd gear.

Quantummechanics is about 10 miles from me. John rebuilt my diff a couple of years ago. I don't think you can find a better British driveline specialist.

Bob

 

[gubba]

Well its done..my winter project to find out why my tranny was grinding when shifting up and down from 2nd to 3d and back again..I tried to go with differant oil and such but to no avail...So the long process of out you come..no easy feat as some kind sole welded the nuts to the bolton the tranny mount so that they would not rattle lose I guess. Much grinding and colorful language I finnaly got the tranny out. With the help of a club member ( BCTR )we dismanteld the whole tranny and overdrive. Here is what we found. Everything looked okay. So we looked further and found two things wrong. One... the syncro rings ( though not worn ) did not sit properly they were oval and rocked thus not getting the grip they needed to shift properly. Second the thrust washer in the overdrive had slipped out of position and had disintigrated. So with 100 bucks in parts and a 300 dollar labor charge ( Thankyou Thankyou ) we reasembled the whole thing and with a new clutch plate pressure plate and throw out bearing I reasembled the whole car back together. Hoping that this was the problem. Well this past week we had two days of sunshine so I took the beast out for a burn to see if the problem had indeed been solved. UREEKA BIG SMILE. Look out for the radar cause she purrs like a kitten now.